The present invention is directed to a method and apparatus for removing a pocket of air from an inner chamber of an artificial heart assembly using a magnetically guided catheter.
After implantation of a blood pump, such as a total artificial heart or a ventricular assist device, into a recipient, the pump is filled with blood. While the pump is filling with blood, a pocket of air may become entrapped in a pumping chamber of the pump. The pocket of entrapped air must be removed before the pump is turned on to prevent the circulation of air bubbles in the blood stream which might otherwise lead to the death or stroke of the blood pump recipient.
A number of methods/devices are currently used to remove such a pocket of air from a blood pump. In one such method, the pump is tilted or manipulated to move the air out of the pumping chamber and into one or more connecting tubes that feed into the pumping chamber where the air is then withdrawn with a vacuum generator such as a syringe. In another such method, used with pumping chambers that are translucent such that the pocket of air can be visually located through a wall of the chamber, a catheter is threaded through an atrial suture line, then through an inlet valve and finally into the pump. Viewing the catheter tip through the pump chamber, the catheter tip is manipulated into the air pocket, and the air is then withdrawn using a vacuum generator attached to an opposing end of the catheter.
However, the method of tilting or otherwise manipulating the pumping chamber is not always possible because in some applications the implanted pump is not freely manipulable. The method of visually locating the catheter tip in the pocket of air is not always viable either because some blood pumps are opaque such that visually-aided positioning of the catheter is not possible.
Thus, there exists a need in the art for a method and apparatus for removing a pocket of air from an implanted blood pump that is not freely manipulable and that has opaque walls.
In one aspect, the invention is directed to a system for removing a pocket of gas from a blood pump having a wall portion with an inner surface and an outer surface and a chamber at least partially defined by the wall portion having a pocket of gas disposed therein; a catheter having a first attractive material that generates a first attractive field; a vacuum generator coupled to the catheter and being adapted to remove the pocket of gas from the chamber when a portion of the catheter is disposed therein; a positioning probe adapted to be disposed at a location outside of the chamber to allow the portion of the catheter to be positioned within the pocket of gas; a second attractive material associated with the probe, movement of the second attractive material causing movement of the first attractive material when the second attractive material is disposed outside the chamber and when the first attractive material is disposed within the chamber; a sensor associated with the probe, the sensor generating a proximity signal having a magnitude relating to a distance between the first attractive material and the second attractive material; an electronic circuit operatively coupled to the sensor, the electronic circuit generating an indicator signal in response to the proximity signal generated by the sensor; and an indicator operatively coupled to the electronic circuit, the indicator generating an indication based on the indicator signal generated by the electronic circuit, the indication relating to the distance between the first and second attractive materials.
In another aspect, the invention is directed to a method of removing gas from a pocket of gas disposed within a chamber of a blood pump using a catheter provided with a first material, the chamber of the blood pump being at least partially bounded by a wall portion and the pocket of gas being located adjacent an inner surface of the wall portion at least partially bounding the chamber of the blood pump, with the method comprising: a) disposing the catheter in the chamber of the blood pump; b) disposing a probe having a second material that attracts the first material of the catheter at a position in which the wall portion at least partially bounding the chamber of the blood pump is disposed between the first material of the catheter and the probe; c) monitoring an indicator to determine if the second material of the probe has attracted the first material of the catheter to a position disposed adjacent the inner surface of the wall portion at least partially bounding the chamber of the blood pump; d) moving the probe to cause the first material of the catheter to be moved so that the catheter is disposed in the pocket of gas; and e) with the catheter disposed in the pocket of gas in the chamber of the blood pump, operating a vacuum generator to cause gas to be removed from the chamber of the blood pump.
The features and advantages of the present invention will be apparent to those of ordinary skill in the art in view of the detailed description of the preferred embodiment, which is made with reference to the drawings, a brief description of which is provided below.